q Partitioning of N. Atlantic into three semi-distinct gyre systems, small exchange resulting in partially isolated geographic populations.
q
q Eastern and Western genetic differentiation based on mt16S rRNA
(Bucklin and Kocher, 1996).
q
 Bucklin et al., 2000, Wiebe et al., 2001
Three-gyre hypothesis

q Genetic differentiation among the gyres based on nuclear pseudo-COI and PGI genes (Bucklin et al, 2000).
First IÕd like to talk about 3-gyre hypothesis. N. Atlantic is conceptually partitioned into three semi-distinct gyre systems:

1) The relatively small Western North Atlantic Gyre is located on the southernmost region of the North Atlantic, including the Gulf of Maine, Nova Scotia, Newfoundland and Gulf of St Lawrence.

2) The northern North Atlantic gyre is the largest gyre system and is bounded by the Labrador and Irminger Seas to the west, with Greenland, Iceland, and the Faroe-Shetland Channel to the north.

3) Most northerly located is the Norwegian Sea gyre, including the North Sea shelf, the Norwegian shelf and fjords, and the Barents Sea.

There is a relatively small exchange of water between northern N. Atlantic and Norwegian Sea gyres. The large scale gyre circulation patterns may be sufficient to partially isolate geographic populations. Therefore, Zooplankton entrained in these gyres may be ecologically, reproductively, and (perhaps) genetically distinct. Previous population genetic studies have also shown some degree of genetic differentiation based onÉÉ